Process for applying ink to ethylene polymer surfaces



Patented May 26, 1953 PRDGE SSlFGR iAB-PLYING .INK TOETI-EZLENE:POLYMER- SURE-AGES N Drawingeg ApplicationMgtrqh cogissop, Serials-No.150,826 c The plastic industry with its variety or iritricaitei shape-50f bars,'-f-rods, sheets; m'olded articles and the likgih tabeeniirineed fdr some time of a suitable rink? :fdr-vprmting, 1'scribihgtistamping or otherwise applying-5 monograms, tra'de marks;

2?? preparedin:acccrd:witiiltheprocess, described in '1 UL. ?S.'?Patent-2,398,893 ofJIRZ Myles et: al'. issuedi Aprir'zsy 1946 While thechloros'ulfoiiatd poly:

IIIIBI'S may be prepared in accord with the process described in McAlevyet'al: U. S; Patent 2,416,060- issued February 18, 1947. Other suitableprocesses maybe used for preparing the chlorinated or chlorosulfonate'dhydrocarbon polymers from ethylene polymers, polyisobutylene,hydrogenated rubberfibuta'd-iene homopolymers or its:"copo1ymers withstyrene or copolymers with the acrylate est'ers. While-the preferredinks of the invention are prepared from the chlorinated andchlo'rosulfbnated hydrocarbon polymers and esand otherindiciabnthese-materials? This-*need-- pecia-lly from-such polymersofethylenerinks-can is particularly urgentin thia mfitkingi,Of PHfSfiGmaterials of'the more max-like --polymers such 'as thoseproducedirom1thes polymers 'of ethylene, from the phloririated and"bhloro'sulfo'nated poly mers thereof; irbm poly-isobutylene -and fromotherfirplalstic materials having'?simiiar surface characteristics. DueItothuwaxdikemmodth surfaceorthese plasticstordinary inksare wholly"unsuitable for permanently.marking-ton applying pictorial orotherrdesignsi'directiypnthem? An robj ect' for the presentsinvention-is -to provide an ink particularly useful/for markinglthesurface of smooth'plastic materials.- Another object of the invention isto provide an ink for general use having new and improved properties.

Still another object is to provide writing-from gravure, intaglio,printing or lithographic inks which contain as onerof their-principal:-ingredients' a ipolymer. orfinterpo'lymer iof:zethylene'; orcaachlorinated 201'; chlorosulfonated productfithereof Other ."obi eatssand-1 aclvantag'es mf ithe: iinvention will :hereinaitenappean Theabove and aothers objectsi-areacc'omplished .1 in accordkwiththeinvention vbyfthpreparationi' of (an: ink containing ia :hydrocarbonwpolymer-ror 40 interpolymenfor toneixthat "has beenchlorinatedfl 011w?chlorosulfo'nated i andrmoretvespecially 2 such 1modified*tltlolyin'er'sor"interpoiymersroti'zethylenest Theserinlrswmaysbecpreparedilgenerally, y -E-the usuaP methods- :ofv preparing;ink. compositionssfi such, for example, as by-mompcunding-pneof-the=raforesaid polymers with a pigment and/or dryer and/or solvent, thecompounding being accompIlshe'd by "preparinga homogeneouspomposition orsuspension by solution, grinding, milling and/or'other'suitable-meansrModified polymer"containinginkswitlimnus properties particularly forprinting scribin" stamping or otherwise"'markingzwaxyisurfaarepreparedctrom chlorinateu hi" drbcarb" npolt v mers' cr'chl'drosulfbnated hydrocarbonpolymers Tlie chlorinaterhy'drmolymersnnayb" r polylmers' described above. Mixtures of these a 0modified or unmodified-polymers maylikewis'ebeused? The ink =contains,in -addition-totheaforesaid 1 polymers" and/or smodified polymers, a"pigment and if a blaek-indieia isdesired, preferably lainpblaolmisincorporated in the composition -0f-kth8 ink-ialthou-g-hother blackssuch as-=cobalt black or. aniline black may: be substituted for lampblack. If a colored indiciais desired anyrapproe priate colored pigment;oxwdye vmay ;.=be alternatively employed: In -addition -to the pigment;a mineral bondingwaagentand/or fille'rwislin some instancesadvantageously added "and more particularly-.3one-harving a goodcovering rpovversuchfz as titanium oxide or: a less iopaqueifillerandpig-wment-suchraszmhite lead:or calciumisulfateu? The inls'mayzbetmadin the formiof a solution orithe modifiedtpolymer in a suitablesolvent,rthe amount-01:solvent.beingxregulatedto give'the de-- siredzibonsistencw Alternatively the ink-im'ayibe prepareaiin'zthe form-refan emulsioniof the pol, meriprrmodifle'd v.polyn'ier inr'watertor 'othersatis"-" faetoryi' non solvent" v of" i the modifiediia olymer. 1' Inksin the form of i pastessandasemi solids may likev'risei-rbewformediby:vincreasing :rthe rratio for polymer tdso'lvent; it

It has been foundtiniaccord -T withlithe-firiveni w tiom thatzzwhilestheabove' described iriksrmay betusedonsprinting.spapergl cardboard andotherinkireceptive surfaees: and williremaim2after:zdr ingin'wellsattacheditorsuchirsurracesg thednkaxlo. not adhere'td-thewax flikesurfaces s as those made ofith'esohd i'polyn'fersfof 'ethyleneiasufirmly as is i dEfslledz -l Ifi subj'ectedoto lrough 1: handling:where itha inked:asurfacedsrrubhed zvigcrously.wlilibccassicnallysmearandfor-rub' off? For -e ample; iscotchittapeiispressed .flonzrthewzinkedii sllltlfa'dfi 'aridd tlinfiremhvd tlie:taperwilh-marmr 3 the ink with it. The inks can be firmly fixed to suchsurfaces by heating the inked plastic surface beyond the drying stage toa temperature between above 50 C. and a temperature just below themelting point of the surface being coated. For fixing these inks to awaxy surface the ink, after printing, is first dried in any suitablemanner by a blast of warm air, for example, or by simply drying at roomtemperatures. After drying, the inked surface is heated to a temperaturesuificient to fix the ink to the plastic surface being printed. Such atemperature ranges between 50 C. to 110 C. or higher and is continuedfor at least 10 minutes at the lower temperature. For fixing achlorinated pol-ymer of ethylene ink to a surface of a polymer ofethylene, for example, temperatures above about 60 C. are preferred.When the temperature is above 100 C. preferably only the printed surfaceis so heated and only for a sufficient period of time to fix the ink tothe surface. The drying and fixing of 4 room temperatures. The driedink, in both instances, had good adhesion to the polymer of ethylene andgood resistance to smearing.

Example 2.-A 40% emulsion containing 80 parts by weight of achlorosulfonated polymer of ethylene and 20 parts by weight of Synvaren631, a liquid phenolic resin, was diluted with water to a solids contentof about 20% and pigmented by the addition of about 40 parts by weightof titanium dioxide. This ink was printed on a film of ethylene polymerwith a rubber stamp and as soon as the impressions were made the filmwas placed in a 65 C. oven and baked for 15 minutes. The resulting printhad good adhesion to the polymer of ethylene and good resistance tosmearing.

Table I illustrates further modifications of the invention and showsseveral types of plastic films and paper printed with inks preparedsubstantially in accord with the process of Examples 1 and 2.

Table I Solvent Coloring gfgfig Substrate Temp.

E a to O 3 on E c: c Resin 1: B i 4 :4 5 z: o '5 n f3 8 E, a g o 5: w E[a '5 O E E? a 8 a a Q a a E 5 2 3 s: a a e 2 e a 2 Q E i; e Q 5.: 5' m5 5 E g a a a i 0 0 '5 4.1 o a: m e1 '5 '3 a" a 0 rs e m o 2 o E- a o 04Z :5 m m 1 3 3 Percent Percent Percent Percent Percent Percent PercentPercent Percent A20% 20 X X x X Al0% X X X X B% I X X X 13-20% X X X13-20% l X X X B-l0% X X X B-5%. X X X 13-10% X X X Bl0% X X X 13-10% gX X X B l0% X X X X B-%+DHAP12% X X X B25%+DHAP12% X X X Bl2%+DHAP6% X XX B-5%+Vistanex-5% X X X Bl6%+Phenolic Resin 4% X X X A=chlorinatedpolythene, chlorine. B=chlorosulfonated polythene, 27.7% CI, 1.5% S.DHAP=dihydro abietyl Vistanex=polyisobutylene, mol. wt.=60,000.

Phenolic resin=Synvaron 631, liquid phenolic resin. the ink may becarried out in separate operations or in a single operation, it beingnecessary, however, to heat the inked surface as stated beyond themerely dried state. These inks may be used for printing the solidpolymers of ethylene in sheet or other form to give a printed designthat when fixed will resist pulling off masking tape, finger nailscratching and rigid bending tests. The inks are particularly usefulwhen used in this manner for screen and rotogravure printing on thesolid polymers of ethylene.

The examples which follow illustrate embodiments of the invention inwhich parts are by weight unless otherwise stated.

Example 1.Titanium oxide pigment to the extent of about 5 parts byweight was blended by stirring into parts of a 10% solution of achlorinated polymer of ethylene in toluene. This viscous mass when thenplaced on a porous stamp pad and with a rubber stamp the surface of afilm of ethylene polymer was marked. As soon as impressions were madethe film was placed in an oven at a temperature of 65 C. and baked forone-half an hour. A film of ethylene polymer was likewise printed andallowed to dry at phthalate-a commercial product obtained from HerculesPowder Co.

In addition to the solvents described in the examples and in theforegoing table other solvents may be used, such, for example, as carbontetrachloride, the halogenated hydrocarbons generally, such, forexample, as trichlorethylene, perchlorethylene, as Well as such solventsas benzene,

xylene, cyclohexane and isopropyl acetate.

The degree of chlorination of the chlorinated hydrocarbon or of thechlorosulfonated hydrocarbon has a marked influence on the solubility ofthe modified hydrocarbon. When used with certain solvents best resultsare realized when the present chlorine content of the modified ethylenepolymer is that of Table II.

The amount of solvent employed is determined, inter alia, by theparticular ink that is to be manufactured. For the preparation of aprinting, stamping or intaglio type ink a high consistency is demandedin order that the ink may remain sufficiently fluid to adhere totheroller or pad, on the one hand, and be readily transferred by stamp,platen or other surface to the article being marked. Usually for suchpurposes from 2 to 8% solvent by weight is sufficient, which solvent isincorporated by solution in the modified polymer, with or withoutheating. On the other hand, if a writing fluid is to be prepared theconcentration of the solvent may be increased up to 25 or 85% by weight.

Drying temperatures for the ink, after its application, will bedetermined in accord with the particular type and variety of inkcompositions employed but generally a temperature between 50 and 90 C.will be ample to dry the ink quickly and to a tackless and resistantsurface in a matter of 30 minutes or less. While drying is important tospeed up printing operations it is very essential, to insure thepermanence of the indicia, that the ink be also fixed when it has beenapplied to wax-like surfaces such as ethylene polymer surfaces. Onemanner of drying and/or fixing the ink to a waxy plastic surface whichhas been printed by the above described inks is to pass the printedsurface over or between rolls heated to a temperature that will dry and/or fix the ink to the surface of the polymer. The temperature of therolls are governed by the speed with which they rotate and by the lengthof time the printed film is in contact with the heated rolls. For theprinting of the polymers of ethylene, roll temperatures between 50 and120 C. are generally employed. In no instance should the printed film,however, be in contact with the heated surface for a period of time thatwill result in permanent distortion of the film due to excessiveheating. Other methods of fixing may be used such as ironing, radiantheating, hot non-solvent bath and the like.

If a pigment is used to provide the color or to give a black ink it maybe ground into the polymer before or after the latter has been put insolution although it is preferable to add the pigment and effect ahomogeneous mixture of it with the modified polymer prior to solution.The amount of pigment incorporated into the ink composition will in eachinstance be governed, by and large, by the type of pigment used and theintensity of color desired in the finished inks. In place of a pigmentthe well known ink colors may be incorporated and when such colors areemployed .a mutual solvent for the modified polymer and the color willfacilitate incorporation. Alippa galls or the other black coloringmaterials described above may be used to provide black and blue-blackinks while the colored inks may be provided by incorporating organicdyes or inorganic metal salts of the desired color into the inkcomposition.

Any suitable method may be used for the preparation of emulsions ofchlorinated or chlorosulfonated polymers of ethylene. This method may beused. Two hundred parts of the chlorosulfonated polymer of ethylene isdissolved in 250 parts of toluene and the solution added with thoroughmixing in a Fred Waring Blendor to an aqueous solution of 210 parts ofwater containing 6 parts of polyvinyl alcohol, 3 parts of Tween, anon-ionic dispersing agent consisting of a polyethylene glycolderivative of a hydrogenated rosin ester. After the emulsion has beenformed the toluene is stripped out of the solution on a steam loath at apressure of about 100 mm. to a solid content of approximately 40%.

The rate of drying, viscosity, tack and stringiness of the ink iscontrolled, by and large, by the choice of solvent employed, for examplecyclohexanone permits higher concentrations of chlorosulfonated polymerof ethylene with higher viscosity and less tack. Other solubilityfactors are of importance in the practice of the invention. Benzene,toluene, xylene and the chlorinated hydrocarbons pucker a film of apolymer of ethylene when applied directly because of rapid penetration.Other less effective solvents, such as methyl ethyl ketone and isopropylacetate do not cause puckering of the ethylene polymer film. Thiseffect, probably caused by the rate of dissipation of the solventthrough the polymer of ethylene, is a factor that should be consideredwhen preparing printing inks where the surface of th print is not opento free evaporation or at least open only a relatively short period oftime. The rate of drying by evaporation is of course controlled byvolatility of the solvent. Consequently, the presence of a small amountof a solvent, such as toluene or carbon tetrachloride, greatly increasesthe amount of the chlorine or chlorosulfonated polymer that can betolerated by the less effective solvents and aid in controlling theviscosity of the resulting inks.

I claim:

1. In a process for printing a solid polymer of ethylene with an inkcontaining in dispersion a pigment and a chlorosulfonated polymer ofethylene, the steps which comprise printing a solid polymer of ethylenebase with an ink containing in dispersion a pigment and: achlorosulfonated polymer of ethylene and thereafter heating the surfaceof the ethylene polymer printed with the dispersion of the pigment andthe chlorosulfonated polymer of ethylene to a temperature between above60 C. and below the permanent distortion temperature of the ethylenepolymer.

2. In a process for printing th surface of a solid polymer of ethylene,the steps which comprise impressing an ink on said surface, the inkconstituting a 40% emulsion containing 80 parts by weight of achlorosulfonated polymer of ethylene and 20 parts by weight of a liquidphenolic resin which has been diluted with water to a solids content ofabout 20%, the ink being pigmented with about 40 parts by weight oftitanium dioxide and thereafter heating the impressed surface of theethylene polymer to a temperature of about C. until the ink is fixed tothe surface.

ALBERT A. PAVLIC.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,416,060 McAlevy Feb. 18, 1937 2,422,919 Myles June 24, 19472,467,875 Andrews Apr. 19, 1949 2,480,007 Fletcher Aug. 23, 19492,486,259 Chavannes Oct. 25, 1949

2. IN A PROCESS FOR PRINTING THE SURFACE OF A SOLID POLYMER OF ETHYLENE, THE STEPS WHICH COMPRISE IMPRESSING AN INK ON SAID SURFACE, THE INK CONSTITUTING A 40% EMULSION CONTAINING 80 PARTS BY WEIGHT OF A CHLOROSULFONATED POLYMER OF ETHYLENE AND 20 PARTS BY WEIGHT OF A LIQUID PHENOLIC RESIN WHICH HAS BEEN DILUTED WITH WATER TO A SOLIDS CONTENT OF ABOUT 20%, THE INK BEING PIGMENTED WITH ABOUT 40 PARTS BY WEIGHT OF TITANIUM DIOXIDE AND THEREAFTER HEATING THE IMPRESSED SURFACE OF THE ETHYLENE POLYMER TO A TEMPERATURE OF ABOUT 65* C. UNTIL THE INK IS FIXED TO THE SURFACE. 